Analysis of Molecular Weight Differences of Hyaluronic Acid

Hyaluronic acid (HA), a biomacromolecule that shines in the fields of life science and materials science, has attracted much attention from researchers and the industry due to its unique structure and function. The difference in HA molecular weight is like a “molecular code”, which determines its performance in different scenarios and unlocks its diverse applications in many fields such as medicine, beauty, and industry. With the continuous deepening of research, this “code” is gradually being deciphered, bringing new opportunities for the development of related fields.

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Basic Knowledge of Hyaluronic Acid (HA)

Hyaluronic acid is a linear high molecular weight polysaccharide composed of N-acetylglucosamine and D-glucuronic acid alternately connected by β-1,3 glycosidic bonds and β-1,4 glycosidic bonds. This seemingly simple repeating structural unit constitutes the unique molecular architecture of HA. From a microscopic perspective, the connection between each repeating unit makes the HA molecular chain present a specific spatial conformation, which not only affects the ability of HA to bind to water molecules, but also determines its rheological properties in solution.

HA’s strong water retention capacity can be called a “miracle” in nature. Studies have shown that 1 gram of HA can absorb up to 6 liters of water under ideal conditions, which is far more than many common moisturizing substances. The principle lies in the abundant hydrophilic groups on the HA molecular chain, such as carboxyl and hydroxyl groups, which can form a large number of hydrogen bonds with water molecules, thereby firmly “locking” the water molecules. In the body, this property of HA plays a vital role. In synovial fluid, it acts like a natural “lubricant”. With its high viscoelasticity, it reduces friction between articular cartilage and reduces wear. According to relevant research data, when the synovial fluid contains sufficient HA, the friction during joint movement can be reduced by about 30%, effectively protecting joint health. In the vitreous body of the eye, HA maintains the shape and transparency of the vitreous body, providing guarantee for the normal functioning of visual function; in the dermis of the skin, it acts as a “water reservoir”, maintaining the moisture and elasticity of the skin, while participating in physiological processes such as cell proliferation, differentiation and migration, which is of great significance to the metabolism and self-repair of the skin.

The molecular weight of HA is measured in Daltons (Da), and its range is extremely wide, ranging from thousands to millions of Daltons. Different molecular weights correspond to completely different physical and chemical properties and biological functions, which has become the core basis for the differentiated application of HA in various fields. The size of the molecular weight directly affects key characteristics such as the length of the HA molecular chain, the viscosity of the solution, and the diffusion ability in the body.

Different Types of Hyaluronic Acid Molecular Weight

♦High molecular weight hyaluronic acid (HMW-HA)
Usually refers to HA with a molecular weight greater than 2 million Daltons. This type of HA exhibits high viscosity and high elasticity in solution due to its long molecular chain. In the field of medical beauty, HMW-HA is the “main force” of injection filling. Taking facial wrinkle filling as an example, after injecting it into the subcutaneous tissue, it can support the collapsed skin tissue with its own high support and effectively improve the appearance of wrinkles.
Clinical research data show that the wrinkle improvement effect after facial filling with HMW-HA can last for 6-12 months. The principle is that the gel-like structure formed by HMW-HA can be maintained under the skin for a long time, providing lasting support for the skin.

♦Medium molecular weight hyaluronic acid (MMW-HA)
The molecular weight is between 500,000 and 2 million Daltons, and it has achieved a clever balance in viscoelasticity and permeability. In the field of cosmetics, MMW-HA is often added to various skin care products. It can form a moderate protective film on the surface of the skin, which can effectively prevent excessive water loss inside the skin, play a good moisturizing role, and will not hinder the skin’s absorption of other nutrients.
In drug delivery systems, MMW-HA has the same advantages. It can better disperse drugs, keep the drugs in a uniform and stable state in the solution, and thus improve the stability and bioavailability of drugs. Experiments have shown that when the drug is combined with MMW-HA, the effective action time in the body is extended by about 50% compared to when it is not combined.

♦Low molecular weight hyaluronic acid (LMW-HA)
The molecular weight range is 10,000 to 500,000 Daltons, while oligomeric hyaluronic acid (oHA) is less than 10,000 Daltons. Their short molecular chains give them strong biological activity and tissue permeability. LMW-HA can penetrate the stratum corneum of the skin, penetrate deep into the bottom layer of the skin, and activate related signal pathways in cells.
For example, it can promote fibroblasts to synthesize collagen and elastic fibers, thereby playing an anti-wrinkle and skin tightening role. oHA performs excellently in regulating inflammatory responses. When inflammation occurs in the body, oHA can inhibit the release of inflammatory factors, reduce the damage of inflammation to tissues, and accelerate the tissue repair process.

Key Factors Affecting the Molecular Weight of Hyaluronic Acid

The extraction source has a significant impact on the molecular weight of HA. Traditional animal-derived extraction, such as extracting HA from tissues such as chicken combs and umbilical cords, has a wide distribution of HA molecular weight due to individual differences in the raw materials themselves, growth environment, and storage conditions. Taking chicken comb extraction as an example, the molecular weight of HA extracted from different batches of chicken combs may fluctuate between hundreds of thousands and millions of Daltons, which poses a great challenge to the consistency control of product quality. In contrast, microbial fermentation, especially the production of HA using streptococcal fermentation, has obvious advantages. By precisely controlling the temperature, pH value, nutrients and other conditions during the fermentation process, the molecular weight of HA can be precisely controlled, and the product purity is high and the batch stability is good. At present, in industrial production, more than 80% of HA is prepared by microbial fermentation, and the wide application of this technology has greatly promoted the development of the HA industry.

The production process is also a key link in regulating the molecular weight of HA. The enzymatic method uses hyaluronidase to specifically cut the HA molecular chain. By controlling parameters such as the amount of enzyme, reaction time and temperature, high molecular weight HA can be degraded into fragments of specific molecular weight. This method has the characteristics of mild reaction conditions and high selectivity, and can obtain products with relatively narrow molecular weight distribution. The chemical degradation method uses strong acids, strong bases or free radicals to break the HA molecular chain, but this method is prone to side reactions, causing changes in the HA molecular structure, which in turn affects its biological activity. Physical treatment methods, such as high-pressure homogenization and ultrasonic treatment, break the HA molecular chain through mechanical force, thereby reducing the molecular weight. This method is relatively mild and has less damage to the molecular structure. It is often used to prepare HA products with high requirements for structural integrity.

The storage and use conditions of HA should not be ignored. During storage, environmental factors such as high temperature, light, and oxidation will accelerate the degradation of HA molecular chains. Studies have found that when the storage temperature exceeds 40°C, the molecular weight of HA will drop by about 20% – 30% within a month. In addition, when HA is used, mixing it with certain chemical reagents or being placed under extreme pH conditions will also accelerate its degradation and change its molecular weight distribution. For example, when the pH value of the HA solution is lower than 3 or higher than 10, the HA molecular chain will break quickly, resulting in a significant decrease in molecular weight.

Functional Properties of Different Molecular Weights

•High molecular weight, viscoelasticity HA forms a protective film that is dense and thick on the surface of the skin. This film acts as a “protective shield” that locks moisture in the skin. It is indispensable in the joint cavity. HMW-HA, as an important component in synovial liquid, can form a lubricating layer on the surface articular cartilage. This reduces friction and wear during joint movements, much like adding “high grade lubricant”. After intra-articular HMW-HA injections, clinical studies show that osteoarthritis sufferers experience significant pain relief and increased joint mobility.

•Its functional properties are based on its water retention and permeability. It can penetrate deeply into the dermis and stimulate fibroblasts, resulting in the production of collagen and elastic fibres. The main substances that maintain skin firmness and elasticity are collagen and elastic fibers. MMW-HA has a similar effect on the skin, which can improve its texture and appearance. MMW-HA is a drug delivery agent that can form a stable compound with drug molecules. This can improve not only the stability of the drugs, but can also improve their uniform distribution in the body.

•Due to their small molecules, oligomeric and low molecular weight hyaluronic acids can penetrate the barrier of the skin to enter cells and play a part. They can activate several signaling pathways within cells, promote cell differentiation, proliferation and migration, as well as accelerate tissue repair. Studies have shown that the addition of LMW-HA and oHA into wound care products can reduce the healing time of the wound by 20% to 30%, and also reduce the likelihood of scarring. They also have biological properties such as antioxidants and anti-inflammatory, which are important for the maintenance and anti-aging of the skin.

Application of Hyaluronic Acid Molecular Weight Differences in Various Fields

The difference in molecular weight of HA determines the different applications methods used in medical cosmetology. Injection fillings of high molecular-weight HA can be used to achieve shaping effects, such as rhinoplasty and lip augmentation. The high level of support it provides can give a more natural appearance. Low molecular HA is added more to skin care products such as facial masks, essences and other products. A low molecular-weight HA essence from a reputable brand was tested in clinical trials and showed that the average skin moisture of the subjects rose by 35% after 28 days of continuous use. The skin’s elasticity increased as well. Low molecular weights of HA penetrate quickly into the lower layer of skin, replenishing moisture and nutrients from the roots.

Pharma is also very specific about how HA’s molecular weight should be applied. High molecular-weight HA can be used to create postoperative antiadhesion products. These materials form a physical barrier over the surgical wound, prevent adhesion of tissues and reduce the risk for postoperative complications. There are currently many products on the market that use high molecular-weight HA for postoperative antiadhesion. The clinical effect of these products is excellent. Low molecular-weight HA can be prepared into eye drops to relieve dry eye syndrome. Its high permeability allows it to quickly penetrate eye tissue, replenish moisture and alleviate symptoms like dry eyes and fatigue. Low molecular-weight HA is also useful as a carrier for drugs. Combining HA with drugs can improve the targeting of the drugs to the diseased tissue and enhance the therapeutic effect.

Cosmetics make full use of HA’s molecular weight characteristics to create a wide range of products. High molecular-weight HA is added to skin care products that have a thick texture, like creams, to create a film that locks in moisture and prevents it from escaping. Low molecular-weight HA is added to essences, toners and other products focusing on absorption so it can penetrate quickly into the deeper layers of skin and play a moisturizing role. Some high-end brands have launched product lines containing multiple molecular HA combinations in order to improve skin care through the synergistic effects of different molecular HA.

HA has a unique value not only in the medical beauty and cosmetics fields, but also in many other areas. Low molecular-weight HA is a food additive that has a number of health benefits. It can be easily absorbed by the body and added to foods and beverages. Low molecular-weight HA can be used in agriculture to improve drought resistance and stress tolerance of plants. In a study, low molecular-weight HA was used to treat wheat seeds. The germination rate increased by 15% and the yield improved under drought conditions.

Summarize

In summary, the difference in hyaluronic acid molecular weight is the core factor that determines its performance and application. From basic structure to functional characteristics, from influencing factors to multiple applications, hyaluronic acid of different molecular weights shows unique value in the fields of medicine, beauty, industry, etc. With the deepening of scientific research and technological innovation, its potential in cutting-edge directions such as precision medicine and personalized skin care is being gradually explored.

As a professional hyaluronic acid raw material supplier, we are well aware of the characteristics and market demand of HA with different molecular weights. Relying on advanced microbial fermentation technology and strict quality control system, we can provide a full range of products covering high molecular weight, medium molecular weight, low molecular weight and oligomeric hyaluronic acid to meet customers’ customized needs in multiple fields such as medicine, cosmetics, and food. If you are looking for high-quality and high-stability hyaluronic acid raw materials, please feel free to contact us. We will provide you with professional solutions and quality services to create more possibilities together.